The invention relates to the art of blow molding wherein a composite plastic article is formed by preparing a plastic parison in a parison mold around and in conformity with a blow core, with a preformed sleeve or liner between the parison and the core, the parison, sleeve and core being subsequently confined in a blow mold and expanded therein, such as disclosed in my copending U.S. Pat. application Ser. No. 71,734, filed Sept. 14, 1970, now U.S. Pat. No. 3,717,544.
The plastic liners may be conveniently formed by thermoforming, in a manner well known in the art. However, a serious problem is encountered in transferring the liners from a thermoforming machine to a remote point of use, that is, to an injection blow molding machine. This problem is particularly difficult to solve when, as is generally the case, the thermoforming operation is conducted at a location remote from the injection blow molding machine and when the liners are fragile or easily deformable. My copending U.S. Pat. application Ser. No. 211,314, now U.S. Pat. No. 3,768,940 filed Dec. 23, 1971, describes a method and apparatus for transferring a preformed liner at the location of the injection blow molding machine to the blow core prior to the molding of the parison in the parison mold. This is accomplished by a device for transferring the liner from the blow mold to the path of the blow core prior to the molding of the parison in the parison mold. This is a particularly ueful method and apparatus; however, this does not solve the problem of transferring the liners from a remote thermoforming machine to the injection blow molding machine.
An additional problem is encountered in the preparation of composite liners, such as liners comprising several layers of different plastics, which are contemplated by said copending application Ser. No. 71,734. Any thermoforming operation generates appreciable amounts of scrap, which may or may not be reusable depending upon its composition and particularly also depending on whether it is composed of a single plastic or of several plastics having different compositions. If the composite scrap cannot be separated into its original components, then, upon reuse, such as by grinding and re-extruding, an inferior product is obtained. In any event, reprocessing, as by grinding and re-extruding, adds appreciably to the cost and inconvenience. If, in addition, it results in a inferior product, as in the case of inseparable composites, it provides an uneconomical burden on the product.
Accordingly, it is a principal object of the present invention to provide a convenient and economical method of transferring liners from point of preparation to an injection blow molding machine.
It is an additional object of the present invention to provide a method of preparing composite liners which enables economical scrap reclamation.
It is a further object of the present invention to enable the convenient transfer of liners as aforesaid, while retaining the ability to economically reclaim the liner scrap.
Further objects and advantages of the present invention will appear hereinafter.